Authorities have issued an all-clear at Children's Hospital of Wisconsin in suburban Milwaukee after an alleged gunman was discovered in the neonatal unit Thursday.

The entire campus was placed on lockdown Thursday after hospital officials reported an "active shooter" at the campus, in the west suburb of Wauwatosa, shortly before noon, Milwaukee County Sheriff David Clarke said.

The Milwaukee Police Department was seeking Hendricks on a warrant for felony possession of a firearm. They found him in the neonatal unit on the hospital's seventh floor, Clarke said. He was holding a baby, the sheriff added.

When officers told Hendricks he was under arrest, authorities say he put the baby down and ran down the hallway with a gun in his hand. Clarke said officers fired several shots when Hendricks turned around with the gun, wounding him in his arm.

"This is not a situation where a guy came in to shoot somebody," Clarke said.

NBC 5 Chicago spoke with Hendricks' attorney, Bridget Boyle, who said he was at the hospital tending to his son who was born premature.

"This guy did not strike me as an individual who was violent," Boyle said.

Hendricks was being treated by staff at Froedtert Hospital & The Medical College of Wisconsin, both of which are connected to Children's Hospital.

There were no injuries to the baby, the baby's mother or hospital personnel, Clarke said.

NBC 5 Investigates has learned that Hendricks has been in and out of court repeatedly over the last four years, and was wanted on an outstanding warrant for failing to appear for his own sentencing on a gun charge just two weeks ago.

Court records show two charges for possession with intent to distribute from January of 2009, but both cases were dismissed.

Two months later he pleaded guilty to charges of cocaine distribution and bail jumping and received a one year suspended sentence and a second sentence of six months in jail.

In December of 2009 he pleaded guilty to a marijuana possession charge, received a 100 day jail sentence and was ordered never to possess another handgun.

Two years later, he was busted for marijuana again, and spent 60 days in jail, and received another warning about owning a gun.

But that warning didn't sink in, and last year Hendricks was found to be in possession of a gun when he ran from police who pulled him over on a Milwaukee street. He pleaded guilty to that charge, but failed to appear at his own sentencing hearing.

That was the outstanding warrant which came up in Hendricks records when officers were called to the hospital Thursday.